DEEP SPACE COMMUNICATION TECHNOLOGIES IN ISAS FOR VENUS AND MERCURY MISSION

摘要

The planetary exploration activity in ISAS was initiated by NOZOMI, Mars atmospheric surveyer launched in 1998. Based on the experience gained through this project, new planetary exploration programs have been investigated to lead our deep space activities in the 21st century. The Venus Climate Orbiter and Mercury Magnetosphere Orbiter are our missions selected for the first decade of the 21st century. In response to this decision, the review on communication capabilities of ISAS has been conducted from the viewpoint of reliability and cost-performance. The development of a new X-band transponder, research-oriented ground system, and turbo decoder test-bed was considered the most effective to support the missions. The X-band transponder is for the optimized and established onboard communication equipment meeting various demands of scientific missions in ISAS. The ground system directly works as a test-base of new communication technologies adopted in the new transponder and also serves as a demonstrator enabling prompt applications of laboratory technologies to missions in the future. The turbo coding scheme will be included in this ground system. The turbo decoder is under development so that its implementation in our ground station will be in time for the Mercury mission. In the following, we will discuss these developments and detailed configurations.